ve a concave appearance on the top. If there is a bulging of the can
it may be due to gas formation, and a small hole should be made in the
can to note any escape of this gas. Should there be any indication of
fermentation, the contents should be discarded. It is advisable to
look with suspicion on cans that appear old, rusty, and soiled; they
are probably left-over stock and liable to be bad. Peas which have
been imperfectly sterilized produce a type of gas which is soluble in
the liquid. After decomposition has occurred there will be no apparent
evidence by the escape of gas, but the liquid will be found to be
excessively acid, and will present a muddy appearance. Certain foreign
importations of canned goods are preserved in color by the
introduction of certain color preservatives. Peas--petits pois, for
example--and the very small string beans which are imported are
intensely green from the copper sulphate used. Its presence may be
detected by adding a few drops of hydrochloric acid to some of the
colored material, then dropping in a bright steel nail, knitting
needle, or knife blade. There will be a deposit of copper salts (like
copper plating) upon the steel if the preservative is present in the
can. Canned corn is often artificially sweetened with saccharine,
which may be detected by shaking several tablespoonfuls of the liquid
in an equal amount of chloroform. Saccharine is soluble in chloroform,
while sugar is not. Allow the mixture to stand a few minutes and
remove some of the chloroform which has settled at the bottom. Place
in a small dish, evaporate the chloroform by gently heating the dish;
taste the residue; if sweet, saccharine is present.

~Coffee~ is adulterated more often when it is put up in ground or
powdered form than when sold in the bean. Real coffee contains a small
percentage of oil, and will float when thrown into a glass of water.
Substitutes generally sink to the bottom. Coffee substitutes are often
made up of starch-containing materials, such as cereals, beans and
peas. This starch may be detected by mixing one tablespoonful of the
suspected coffee in a little cold water, adding one cup of boiling
water; allow it to boil two minutes, filter through cotton, and pass
the liquid through charcoal to remove the color. When it is cold, add
a few drops of dilute iodine solution. If starch is present, a blue
color will appear.

METHODS USED IN THE PREPARATION OF FOOD

Food is prepared for consu